Docking system for airport terminals

ABSTRACT

A docking system for airport terminals has a docking station subsystem and a docking station for each gate. The docking station subsystem is connected via a communication network to a central working position (control device). The docking station subsystem includes an airfield situation monitoring and processing segment ASMPS, at least one advisor and guidance display segment AGDS, a data and status handler segment DSHS having at least one video camera for each center line of the gate, and at least one ground operation panel segment GOPS. The docking station subsystem has an auxiliary subsystem connected to it, by which information relating to aircraft models and the gate can be entered in the docking station subsystem. A docking guidance system is connected to other systems of an airport and includes a docking guidance subsystem for each gate of the airport.

[0001] This is a Divisional of U.S. application Ser. No. 09/755,096,filed Jan. 8, 2001, which is a Continuation in Part of U.S. applicationSer. No. 09/533,245 filed Mar. 22, 2000, which, in turn, is aContinuation of International Application PCT/DE98/02822, with aninternational filing date of Sep. 22, 1998. The disclosures of thesethree prior Applications are incorporated into this application byreference.

FIELD OF AND BACKGROUND OF THE INVENTION

[0002] The invention relates to new and useful improvements in a dockingsystem for airport terminals. More particularly, the invention relatesto a docking system for airport terminals having a positioning apparatusby which an aircraft can be guided to a parking position appropriate forits type, a video device by which the aircraft can be detected as itapproaches the airport terminal, and an evaluation unit by which it ispossible to evaluate data which are supplied to the evaluation unit bythe video device and which relate to the form and the movement of theaircraft.

[0003] German Patent DE 40 09 668 A1 discloses a procedure in which avideo camera is used to detect a two-dimensional image, which is passedto an evaluation unit.

OBJECTS OF THE INVENTION

[0004] An object of the invention is to further develop the knowndocking system. A further object is to develop the known system in sucha manner that it can be used even in adverse environmental and weatherconditions with an extremely high operational reliability, sufficientfor the operation of airports.

SUMMARY OF THE INVENTION

[0005] These and other objects are achieved according to one formulationof the invention in that a template set for each different type ofaircraft is stored in the evaluation unit, which set contains at leastthree, preferably five, specific templates for all types of aircraft oroutline sections of the relevant type, and in that the at least three,preferably five, specific outline sections of the aircraft which isapproaching the airport terminal can be determined and compared with thestored template sets, in the evaluation unit, from the input signalsfrom the video device.

[0006] According to another aspect of the invention, a docking system isprovided for airport terminals, which has a comparatively low level ofinstallation complexity and, furthermore, allows the airport terminalsto be operated in a safe and, for the most part, automated fashion.Precise detection of the type of aircraft approaching the airportterminal is ensured even if the entire contour of the approachingaircraft cannot be detected by the video device, for example becausethere are obstructions in the parking area or ramp area of the airportterminal.

[0007] A monochrome camera has been found to be a particularly suitablevideo device for implementing the docking system according to theinvention and its positioning apparatus.

[0008] The objective focal lengths of the video device shouldadvantageously be 16 or 25 mm.

[0009] Adequate detection of the aircraft approaching the airportterminal is ensured if the video device is arranged such that it isapproximately aligned with the center line of the airport gate,preferably at a height of approximately 9 m.

[0010] The type of aircraft approaching the airport terminal can bedetected with a comparatively low level of complexity if a sequence ofgray tone images produced by the monochrome camera can be read to theevaluation unit, the individual gray tone images in the sequence can bespatially filtered in order to extract gray tone edges, the sequence ofgray tone images can be filtered in the time domain in order to producemoving images, and a mask can be produced from the moving imagesdefining areas for subsequent segmentation.

[0011] The evaluation unit should expediently have a Sobel filter forspatial filtering of the gray tone images, and for filtering the graytone images in the time domain.

[0012] Two engines, the windshield and two landing gear legs have beenfound to be outline sections which are particularly specific to theaircraft contour of each type. These five specific outline sections ortemplates expediently form a template set. This template set is definedfor the respective aircraft type and stored in the evaluation unit.

[0013] Trajectories of the templates or specific outline sections of theaircraft contour can be used as a basis to determine the presentposition of the aircraft as it approaches the airport terminal.

[0014] When the docking system according to the invention, in particularits positioning apparatus, is implemented and installed completely, itis possible to allow all the processes required for docking of theaircraft, in particular the docking of the bridge to the aircraft, to becarried out automatically. In this case, it is possible for the videodevice to have only one video camera.

[0015] In a particularly advantageous manner, the pixel processingdescribed above as well as the detection of the type of aircraftapproaching the gate of the airport terminal can be used for a dockingsystem for airport terminals wherein each gate has a docking stationsubsystem. The docking station subsystem is connected via acommunication network to a central control device. In addition, it hasan airfield situation monitoring and processing segment, at least oneadvisor and guidance display segment, a data and status handler segmenthaving at least one video camera for each center line of the gate, andat least one gate operator panel segment. An auxiliary subsystem isconnected to the docking station subsystem, by which informationrelating to aircraft models and the gate can be entered into the dockingstation subsystem.

[0016] The docking station subsystem expediently has an advisor andguidance display segment for each center line of its gate.

[0017] A particularly advantageous embodiment of this advisor andguidance display segment is achieved if a microprocessor is providedwhich controls the display elements and converts display commands intoindications of the display elements.

[0018] An embodiment of the docking station subsystem according to theinvention and of the docking system according to the invention which isless complex in terms of equipment and design is achieved if the dataand status handler segment of the docking station subsystem runs on thesame hardware as the airfield situation monitoring and processingsegment. Also, in this embodiment, the communication between the dockingstation subsystem and the central control device takes place via thecommunication network, and the processes within the docking stationsubsystem are coordinated by the data and status handler segment.

[0019] In a further development of the docking system according to theinvention, the data and status handler segment and the airfieldsituation monitoring and processing segment of the docking stationsubsystem may be arranged in one housing.

[0020] Expediently, the data and status handler segment and the airfieldsituation monitoring and processing segment may run on a hardware basiscomprising a PC motherboard and video signal processing equipment.

[0021] If the design of the docking station subsystem for the dockingsystem according to the invention provides for the data and statushandler segment and the airfield situation monitoring and processingsegment to be arranged outside the actual gate, it is possible toadditionally arrange the advisor and guidance display segment in thehousing common to the two components mentioned above.

[0022] In a further specific embodiment of the docking system accordingto the invention, the docking station subsystem is designed such that itallows advisor and guidance displays to be transmitted to a screen inthe cockpit of an aircraft which is approaching the gate. This mode ofoperation may be used instead of operating the advisor and guidancedisplay segment, or may be provided in addition to operating thisadvisor and guidance display segment.

[0023] It is also possible to arrange the airfield situation monitoringand processing segment in a housing with the video camera.

[0024] For transmission of data between the airfield situationmonitoring and processing segment and the data and status handlersegment of the docking station subsystem, it is expedient for theairfield situation monitoring and processing segment to have anassociated digital signal processor. In the digital signal processor,the originally analog video signals are converted into digital signalsbefore they are passed to the input line to the data and status handlersegment.

[0025] The auxiliary subsystem which is associated with the dockingstation subsystem of the docking system according to the inventionpreferably has an aircraft model output, a gate installation planner, acalibration unit and a validation and diagnosis tool. The communicationnetwork of the docking system according to the invention isadvantageously in the form of a high-speed network using an asynchronoustransmission mode, by which originally digital signals and originallyanalog signals converted into digital signals can be transmitted, e.g.video signals.

[0026] The ATM high-speed network may advantageously have at least onenetwork adapter in the form of a SICAN-ATMax 155-PM2.

[0027] The docking station subsystem of the docking system according tothe invention is systematically and expediently broken down into aground area monitoring and processing segment, a gate area controlsegment, a gate schedule segment and a gate data handler segment.

[0028] The ground area monitoring and processing segment advantageouslyhas an airfield monitor and an airfield situation processor, which isconnected by means of an interface to the gate schedule segment.

[0029] The gate area control segment of the docking station subsystem ofthe docking system according to the invention has airfield groundlighting, an advisor and guidance display, a ground operator panel, aluxometer and a gate area processor. The gate area processor runs on aPC platform to which the airfield ground lighting, the advisor andguidance display, the ground operation panel and the luxometer areconnected. In addition, the gate area processor is connected by aninterface to the gate schedule segment.

[0030] The gate data handler segment should advantageously have acalibration support and static data handler, which run on a PC platformand are connected in each case by means of one interface to the gateschedule segment.

[0031] The gate schedule segment of the docking station subsystem of thedocking system according to the invention has gate management and awatchdog.

[0032] In accordance with another formulation of the present invention,a docking guidance system includes a plurality of stand alone systems,which are associated with respective gates of an airport. These standalone systems are interconnected by a network. If an aircraft approachesa particular gate, at which it is to be docked, the respective standalone system guides the aircraft to its proper final parking position atthe particular gate. To this end, the respective stand alone systemreceives guidance data regarding the guidance of the aircraft, e.g.,data from a video camera, which attempts to recognize the aircraft typeand which monitors the current position and movement of the aircraft.

[0033] In the case of large and mid-sized airports, these guidance dataare forwarded to a central working station, which monitors and controlsthe overall operation of the docking guidance system. In addition, thecentral control device exchanges data with external airport systems,such as a surface movement guidance and control system (SMGCS) and acentral monitoring system (CMS). In the case of large airports, whichhave many terminals, the central control device also exchanges data withoperator stations at each terminal. In the case of mid-sized airports,only one operator station is provided, which is located at the centralcontrol device, for example. By processing all these data from thedifferent systems of an airport, the central control device is capableof performing its central monitoring and control function for the docketguidance system.

[0034] In the case of small airports, it is possible to dispense with anoperator station and a central control device. Instead, all the standalone systems communicate directly with each other over the networkconnecting the stand alone systems. In this way, a docking process of anaircraft, which is in progress at a particular gate, can be monitoredand, if necessary, influenced by an operator present at another gate,for example.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention and further advantageous embodiments of theinvention according to the features of the dependent claims areexplained in more detail below with the aid of diagrammatic, exemplaryembodiments in the drawings, in which:

[0036]FIG. 1 shows a basic illustration of the docking system accordingto the invention, and its integration in an airport network;

[0037]FIG. 2 shows a basic illustration of an aircraft approaching agate of an airport terminal;

[0038]FIG. 3 shows a basic illustration of the method for finding anaircraft outline of an aircraft approaching a gate;

[0039]FIG. 4 shows a sequence for searching for the aircraft outline ofthe aircraft approaching the gate, and for initiation of tracking andfollowing the aircraft found;

[0040]FIG. 5 shows a data flowchart of the docking system according tothe invention and its integration in the communication network of anairport;

[0041]FIG. 6 shows a basic illustration of the major components of thedocking system according to the invention;

[0042]FIG. 7 shows a first embodiment of a docking station subsystem ofthe docking system according to the invention;

[0043]FIG. 8 shows a second embodiment of the docking station subsystemof the docking system according to the invention;

[0044]FIG. 9 shows a third embodiment of the docking station subsystemof the docking system according to the invention;

[0045]FIG. 10 shows a systematic segment structure of the docking systemaccording to the invention;

[0046]FIG. 11 shows a ground area monitoring and processing segmentGAMPS of the docking station subsystem illustrated in FIG. 10;

[0047]FIG. 12 shows a gate area control segment GACS of the dockingstation subsystem illustrated in FIG. 10;

[0048]FIG. 13 shows a gate data handler segment GDHS of the dockingstation subsystem illustrated in FIG. 10;

[0049]FIG. 14 shows a gate schedule segment GSS of the docking stationsubsystem illustrated in FIG. 10;

[0050]FIG. 15 shows a schematic overview of an arrangement of thedocking guidance system according to the present invention in relationto other systems of an airport;

[0051]FIG. 16 shows a software structure of the docking guidance systemaccording to the present invention configured for large airports havingmultiple terminals;

[0052]FIG. 17 shows a software structure of the docking guidance systemaccording to the present invention configured for mid-sized airports;

[0053]FIG. 18 shows a software structure of the docking guidance systemaccording to the present invention configured for small airports;

[0054]FIG. 19 shows a preferred architecture of a central control deviceof the docking guidance system according to the present invention;

[0055]FIG. 20 shows an overview of a preferred embodiment of a SiemensDocking Guidance System (SIDOGS);

[0056]FIG. 21 shows an exemplary screen display of a central controldevice of the SIDOGS of FIG. 20; and

[0057]FIG. 22 represents a preferred calibration system for calibratingthe angular field and/or position of a TV camera or video camera of thedocking guidance system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] An airport terminal 2 integrated in an airport network 1 as shownin principle in FIG. 1 is equipped with a docking system by which, via abridge, a connection to the interior of an aircraft 3 can be produced(FIG. 2).

[0059] In order to position the aircraft 3 correctly for the dockingprocess at the airport terminal 2, all the gates 4 of the airportterminal 2 each have an associated positioning apparatus, by which theaircraft 3 that is intended to be docked can be guided to a stopping orparking position 5 appropriate to its type.

[0060] To this end, the positioning apparatus has a video device 6,which, in a preferred embodiment, is in the form of a monochrome camera,by which the aircraft 3 can be detected as it approaches the gate 4 ofthe airport terminal 2. The positioning apparatus additionally includesan evaluation unit 7 by which data supplied to it from the video device6 and relating to the form and movement of the aircraft 3 can beevaluated. Finally, the positioning apparatus includes a display 8 bywhich a pilot of the aircraft 3 can be provided with informationrequired to move the aircraft 3 to the intended parking position 5.

[0061] Since the parking position 5 differs depending on the type ofapproaching aircraft 3, the positioning apparatus first of all has todetermine the type of aircraft 3 that is approaching. To do this, thevideo device 6 is used to produce gray tone images onto which theaircraft 3 that is approaching the gate 4 is mapped. By means of thevideo device 6, a sequence of gray tone images, showing differentpositions of the aircraft 3 that is approaching the gate 4, is read intothe evaluation unit. Evaluation of this sequence of gray tone imageswithin the evaluation unit allows moving edges to be detected, whichcorrespond to the outline of the aircraft 3 that is approaching the gate4. This is done firstly by using spatial filtering, by which the spatialedges in the individual gray tone images are found. Filtering in thetime domain is used to extract edges which move over time, so that it ispossible to distinguish between moving and stationary objects. Thismakes it easier to determine an aircraft outline from the gray toneimages. Each type of aircraft has a specific aircraft outline which, forits part, has specific outline sections or templates. For selectingsuitable templates, a template set may be formed, to provide examples ofthe respective types of aircraft. This template set may contain three,or preferably five, individual templates.

[0062] A template set is stored within the evaluation unit 7 for eachtype of aircraft. The aircraft contour determined for the aircraft 3approaching the gate 4, or the template set resulting from this, is nowcompared with the template sets stored within the evaluation unit. Asthe result of this comparison operation, the type of aircraft 3approaching the gate 4 of the airport terminal 2 is determined. Thistype has a specific associated parking position 5. Details are nowindicated on the display 8 to allow the aircraft captain or pilot tomove his aircraft 3 to this parking position 5.

[0063] The aim of the following text is to describe in detail how edgeoperators in spatial space are used to extract the stationary gray toneedges from the gray shade images, in order to obtain the aircraftcontour.

[0064] A Sobel operator can advantageously be used for this purpose,which is not derived from a mathematically closed form. This Sobeloperator has the following forms: Form 1: −1, −2, −1   0,   0,   0   1,  2,   1 Form 2: −1, −0, −1 −2,  0,  2 −1,   0,   1

[0065] Form 1 extracts edges located horizontally in the gray toneimage, and form 2 extracts edges located vertically in the gray toneimage. This is done by means of a weighted first derivative in therespective coordinate direction under consideration. Both Sobeloperators have been applied to the gray tone image, and their resultshave been linked alternately by pixels:$b_{i,j} = {\frac{\sqrt{b_{1,i,j}^{2} + b_{2,i,j}^{2}}}{\sqrt{2}}.}$

[0066] Moving edges can be extracted not only by considering a gray toneimage, but also by considering a time sequence of gray tone images. Thefilter cores therefore have to have a time dimension. Not only filtercores which have only one time dimension, but also filter cores whichhave time and space dimensions were investigated.

[0067] A Laplace filter, a Mexican hat operator or a HildrethMarroperator and a Sobel operator have been found to be particularlyexpedient as filter cores. In the latter case, the concept of atwo-dimensional edge filter which operates with a weighted firstderivative was expanded to three dimensions. This results in thefollowing operator core in three dimensions of size 3×3×3: −1, −1, −1−1, −8, −1 −1, −1, −1 t = 0   0,   0,   0   0,   0,   0   0,   0,   0 t= 1   1,   1,   1   1,   8,   1   1,   1,   1 t = 2

[0068] Filtering using the Sobel filter produced the best results forboth the spatial and time edges.

[0069]FIG. 3 shows the fundamental program sequence for determining theaircraft contour.

[0070] A gray tone image sequence which has been recorded by the videodevice 6 is passed via a video input to the evaluation unit 7. There,this gray tone image sequence is subjected to spatial filtering, bywhich spatial edge filtering of the respective gray tone image iscarried out. The result of this spatial edge filtering represents themagnitude of a Sobel operator in the x direction and y direction, and isstored. This spatial edge filtering is used to extract gray tone edges,which are available as an intermediate result.

[0071] Time-domain edge filtering of successive grayshade images iscarried out in the time-domain filtering which follows the spatialfiltering. The result of this time-domain edge filtering represents themagnitude of a Sobel operator expanded by the time direction, and isstored. An intermediate result is once again available as the result ofthe time-domain edge filtering.

[0072] The thresholding which follows the time-domain filtering is usedto produce a binary image from the gray tone image. The digitizationthreshold is defined by the variable threshold value. For gray shadesbelow this threshold value, a low value is entered in the output binaryimage, and a high value is entered in it for values which are equal toor exceed the threshold value. The thresholding provides a furtherintermediate result.

[0073] The thresholding is followed by the functional stage ofdilatation, in which the binary image produced in the course ofthresholding is subjected to dilatation with a size of one pixel, thatis to say all those areas which have a gray level greater than zero areenlarged by one pixel at their boundaries. The functional stage ofdilatation provides an intermediate result, which corresponds to themask or outline contour of the aircraft 3 approaching the airportterminal 2 or its gate 4.

[0074] The aircraft contour is positioned by the method whose principleis illustrated in FIG. 4. In this case, it is assumed that the aircraft3 that is approaching the gate 4 of the airport terminal 2 will turn inat the latest at a predetermined minimum distance from the parkingposition in the region of the gate 4. It is also assumed that theaircraft captain or pilot will in the process orient himselfapproximately on the center line of this gate 4. To do this, a catchmentposition is defined on this center line. A search area is defined aroundthis catchment position, in which area the features that define theaircraft contour or the aircraft type are searched for. The defined sizeof this catchment area depends on the permissible lateral error for theaircraft 3 that is approaching the gate 4.

[0075] The individual templates which form the template set for anaircraft type must be chosen such that they are not invariant withrespect to displacements. Furthermore, they are chosen to have a highcontrast in the sequence of gray tone images. In addition, the selectedfeatures or templates must be highly tolerant to external influences,such as lighting and weather. The following features and individualtemplates have therefore been chosen for the aircraft types so farincluded in the form of template sets:

[0076] The two engines, the windshield and the two landing gear legs. Anindividual template set is produced for each aircraft type by theseindividual templates.

[0077] The aircraft 3 is now looked for around the position defined inthe ramp area. Since the aircraft 3 is a rigid body, a fixed arrangementof the chosen features can be predetermined. These features may appeardistorted only due to the orientation of the aircraft 3 with respect tothe video device 6. For this reason, it is desirable to find an optimumor elastic grid. In order to achieve this aim, the system looks for themaximum cross-covariance value in a defined search area around eachtemplate. The sum of all the cross-covariance values is a measure ofwhether the aircraft type has been found. By using an elastic grid, itis also possible in the process of “position determination” that followslater to determine the orientation of the aircraft 3. This orientationinformation may in turn be used for better tracking.

[0078] The search is carried out in the spatial Sobel-filtered image,which reproduces the gray tone edges and is thus considerably lesssensitive to lighting influences than the underlying edge image. Incomparison to other operators, the spatial Sobel-filtered image has thebest edge contrast with the best noise suppression.

[0079] The position of a template is determined by shifting the templateover the edge image until the similarity measure assumes a maximum. Thecross-covariance is used as the similarity measure for this purpose,since this forms a better maximum/environment contrast thancross-correlation. It also has a better maximum-to-noise ratio comparedto Euclidean distance.

[0080] The data flowchart illustrated in FIG. 5 shows how individualfunctional components of the docking system according to the inventioncommunicate with other functional components of this system and withfurther functional components of an airport control system outside theactual docking system.

[0081]FIG. 5 is subdivided into a first phase and a second phase, as isshown by the dotted boundary lines in FIG. 5. The lower part, whichdescribes the first phase, of FIG. 5 is the major element for thedocking system according to the invention, since the major functionalelements of the docking system itself are illustrated there. Incontrast, the upper part of FIG. 5 shows a central control device(central working position CWP) of an airport, which is connected to thedocking system according to the invention. The central control device(CWP), for its part, is related to the airport control system via acentral monitoring and surveillance system interface (CMSI) and a userdefined interface (UDI).

[0082] In the illustration in FIG. 5, the docking system according tothe invention is broken down into four functional units. First of all, afunctional unit comprising a docking status/data handler (DSH) andcalibration support (CS) is provided there. This functional unitreceives central control signals, database updates and monitoring andsurveillance data relating to the respective gate (gate i CMS data) fromthe CWP. From this functional unit DSH, CS the CWP receives statusdetails relating to the respective gate (gate i statuses), live videosignals from this gate (gate i live video) and central monitoring andsurveillance data relating to this gate (gate i CMS data).

[0083] The functional unit DSH, CS has a calibration input and an outputto a calibration display. Furthermore, the functional unit DSH, CSoutputs recorded video sequences as well as control signals for theairfield ground lighting (AGL control). The DSH operates together with afurther functional unit, namely the airfield situation processor (ASP)on a PC based system. The functional unit ASP receives from the DSH ofthe functional unit DSH, CS control signals for the ASP (ASP control),initialization data and black-and-white video data (B & W Video Data).The DSH of the functional unit DSH, CS receives from the functional unitASP tracking results as well as ASP check results.

[0084] Furthermore, data relating to the gate configuration are enteredin the functional unit DSH, CS while, in contrast, said functional unitoutputs data relating to the docking process (docking log data).

[0085] As a further functional unit, the docking system according to theinvention has a ground operator panel (GOP) from which transfer data areentered in the functional unit DSH, CS, and which receives transfer datafrom the functional unit DSH, CS. Furthermore, operation commands andtest commands are entered in the GOP, while the GOP outputs the dockingstatus, test results and an aircraft type table (a/c type table).

[0086] An advisor and guidance display (AGD) is provided as a furtherfunctional unit of the docking system according to the invention, whichenters self test results in the functional unit DSH, CS and receivesfrom this functional unit data to produce the characters for the displayinformation (display information character generation data). The AGDoutputs guidance and verification signals and test patterns. A preferredembodiment of a display of the AGD is described in more detail inconnection with FIG. 20.

[0087] As can be seen from FIG. 6, the docking system DGS according tothe invention in principle has three partial operating systems, namely adocking station subsystem (DSS), a central controller working positionsubsystem (CWPS) and a communication network subsystem (CNWS). The DSScontains all those system segments which are arranged at the gates. TheCWPS comprises a display and control system which is based on aworkstation and is provided in a central control room at the airport.The CNWS is the network which connects these two subsystems to oneanother, in order to transmit data between these subsystems.

[0088] An auxiliary subsystem (AuxS) associated with the DSS contains anumber of auxiliary functions, for example the production of newaircraft models, the gate configuration and maintenance.

[0089] The DSS is connected on the one hand to the airfield situation,and on the other hand to the maintainer, calibrator, bridge personnel,ground personnel, (co-)pilot and the AGL. The gate specifier, theaircraft model specifier (a/c model specifier), the installationpersonnel and the research department can be connected to the DSS viathe AuxS.

[0090] The CWPS of the docking system according to the invention is onthe one hand connected to the administrator, the maintainer, thesupervisor and the controller. On the other hand, it is connected to thecentral monitoring and surveillance system, the airport database, userdefined gate systems, the AGL, time reference systems, and a surfacemovement guidance and control system (SMGCS).

[0091] The DSS serves two or more central lines or center lines for thegate. Two center lines or central lines can be served by one DSS,provided the two are mutually dependent and/or provided the one cannotbe used while the other is in use.

[0092] As can be seen from FIGS. 7, 8 and 9, the DSS has four differentsegments: the airfield situation monitoring and processing segment(ASMPS); the advisor and guidance display segment (AGDS); if there aretwo mutually dependent central or center lines, a second AGDS may berequired, depending on the configuration and/or arrangement of thecentral or center lines at the gate. The AGDS contains an integratedmicroprocessor, which controls the display elements and converts displaycommands into displays; the data and status handler segment (DSHS) withone or two video cameras for each central line or center line; thenumber of video cameras for each central line or center line depends onthe aircraft types which may dock at the respective gate; the DSHS runson the same hardware as the ASMPS. It provides the communication betweenthe DSS and the CWPS via the CNWS, and coordinates the processes withinthe DSS.

[0093] The gate operator panel segment (GOPS) is a microprocessor-basedsystem having a small keyboard or keypad and a liquid crystal displayLCD, which transmits only the input data to the DSHS and outputs thedata from the DSHS to the LCD.

[0094] Three different embodiments of the docking station subsystem DSSdiffer essentially by the arrangement of the ASMPS and DSHS.

[0095] A first embodiment, illustrated in FIG. 7, provides for the ASMPSand the DSHS to be arranged in the same housing together with and at thesame location as the AGDS, as can be seen from the double linesurrounding said segments in FIG. 7.

[0096] The ASMPS and the DSHS run on a PC motherboard and on the videoprocessing equipment which comprises, for example, a so-called framegrabber; interface elements are provided to the GOPS 1 to 4, to the AGDS1 and 2, to the auxiliary interface and to the CNWS, but without anymechanically operating parts.

[0097] The auxiliary interface can be used, for example, to calibratethe video camera 9 and the further video camera 10, or to test the DSS.If the DSS is operated on its own, the auxiliary interface may be usedto input the gate configuration and the aircraft database, or to outputrecorded video sequences. The AGDS has a simple microprocessor andthree, or possibly four, LED arrays. The simple microprocessor providesthe communication with the DSHS and controls the LED arrays.

[0098] RS 232, RS 422 and RS 485 type interfaces, or interfaces based onoptical links, may be used as the interface between the DSHS and theGOPS 1 to 4 or the AGDS 2. An RS 232 type interface may be used as theinterface between the DSHS and the AGDS.

[0099] The second version or embodiment of the docking station subsystemillustrated in FIG. 8 has a common housing just for the ASMPS and theDSHS, as can be seen from the double line which surrounds the twosegments in FIG. 8. These two segments are arranged separately from theother equipment in an equipment room. The AGDS is, furthermore, arrangedin the outer gate area, of course. It can be seen from this that theinterfaces between these segments differ from those in the firstembodiment. The interface between the AGDS and the DSHS now correspondsto the other RS 232, RS 422 etc. type interfaces.

[0100] A video monitor 11 and a keyboard or keypad 12 are now providedinstead of the auxiliary interface, and can carry out the functions ofthe auxiliary interface provided in the first embodiment.

[0101] In the third embodiment of the DSS illustrated in FIG. 9, theASMPS is accommodated inside a housing 13 or 14, respectively, of thevideo camera 9 or 10, respectively. The required software runs on adigital signal processor, which transmits the aircraft positiondigitally to the DSHS. The DSHS may be in the form of a PC ormicroprocessor board of relatively low performance. In principle, it isalso possible to accommodate the DSHS in a housing with the AGDS or theAGDS 2.

[0102] The major difference between the described embodiments is thearrangement of the hardware that forms the ASMPS and the DSHS. There aremore minor differences in the auxiliary interface and in the interfacebetween the AGDS and the DSHS.

[0103] The first embodiment requires the capability for the hardwarethat forms the ASMPS and the DSHS to operate in outdoor environmentalconditions.

[0104] The advantage of the first embodiment is that it involves only aminimum level of installation complexity. The interface between the AGDSand the DSHS has a simple configuration. On the one hand, thereliability may be greater since less installation complexity and nomechanically operating equipment parts are required. On the other hand,operation is required in outdoor environmental conditions; this reducesthe reliability, even if cooling or heating measures are provided.

[0105] The auxiliary subsystem which is used as the auxiliary systemAuxS is required to start and to maintain the system during systeminstallation and during system maintenance. It comprises an aircraftmodel editor (AME), a gate installation planner (GIP), a calibrationtool (CT), a validation and diagnosis tool (VDT) and a maintainersupport tool.

[0106] The AME may be installed on a separate PC. In the secondembodiment of the DSS, the aircraft model may be transmitted by means ofa floppy disk to the operating system, while in the first and thirdembodiments it may be transmitted by means of a laptop PC and theauxiliary interface. If all the isolated systems are connected by anetwork, such data can be integrated via the CWPS.

[0107] The GIP produces a hard-copy installation plan and the gateconfiguration on a disk. The gate configuration may be entered in theoperating system in the same way as the aircraft models.

[0108] The VDT may run on a separate PC. The data may be entered in thisPC via the auxiliary interface if the system is isolated, or may beinput via the CNWS and CWPS. In the second embodiment of the DSS, theVDT may also run on the isolated system.

[0109] The CT supports the calibration process with a graphics display.The calibrator can carry out the calibration interactively. Thecalculated calibration data remain in the DSS.

[0110] The CNWS may be in the form of an ATM network, in which at leastone switching unit may be provided. A UNI 3.1 or UNI 4.0 should be usedfor signaling. 155 Mbit/s or 25 Mbit/s adapters may be used, dependingon the bandwidth requirements. The distances which can be achieveddepend on the transport medium: monomode fibers for long distances,multimode fibers for medium distances, or twisted double wires for shortdistances.

[0111] The advantages of such a high-speed ATM network are that longdistances are possible, no electromagnetic interference occurs, DCisolation is provided, a guaranteed bandwidth is ensured between twodata end points, and a guaranteed delay is ensured between two data endpoints.

[0112] The CWPS may run on a PC system using the Windows NT operatingsystem. Furthermore, a Video-HW-ProVisionBusiness and an ATMax 155-PM2ATM adapter from SICAN GmbH are preferably used as hardware components.

[0113] In the DSS illustration chosen in FIG. 10, the subsystem levelillustrated in FIGS. 7 to 9 has been omitted; based on the illustrationin FIG. 10, the DSS has the following segments: a ground area monitoringand processing segment (GAMPS), a gate area control segment (GACS); agate schedule segment (GSS), a gate data handler segment (GDHS), acommunication network segment (CNWS), a central working position segment(CWPS); and an auxiliary functionalities segment (AuxS).

[0114] The GAMPS illustrated in FIG. 11 has airfield monitoring (AM) andan airfield situation processor (ASP). This supports the followingfunctions: frame grabbing, calculation of the display information fromthe position data which is provided by the ASMPS, processing of theairfield situation, calculation of real-world positions, and videorecordings.

[0115] The GAMPS assists the GSS in investigating the airfield situationduring the docking sequence. It provides self-test and calibrationinformation as well as video images for calibration of the GSS. Inaddition, the GAMPS supplies the AuxS with recorded video sequences.

[0116] The GACS comprises the airfield ground lighting (AGL), theadvisor and guidance display (AGD), the gate operator panel (GOP), theluxometer (LM) and the gate area processor (GAP). The GAP runs on a PCplatform to which the AGL, the AGD, the GOP and the LM are connected.

[0117] The GACS supports the following functions: Measurement of thelight intensity in the area of the gate; Switching for the AGL; Displayof guidance and verification details for the aircraft pilot and displayof test patterns for the ground personnel, with one or two AGDs beingprovided; Input of operating and test commands by the ground personnelvia one to four GOPs, output of test results and docking status to theground personnel via the GOP, self-testing of all parts of this segment,and communication and data interchange with the GSS.

[0118] The GACS has to measure the light intensity in the gate area, andconvert it into dark or light information. The GACS converts the GOPinputs and forwards them to the GSS. On the other hand, the GACSreceives commands from the GSS, interprets them, and passes thecorresponding display information to the AGD and to the GOP, switchesthe AGL on or off, and tests the communication lines to the AGD and GOP.

[0119] The GDHS illustrated in FIG. 13 has a calibration support (CS)and a static data handler (SDH), both of which run on a PC platform.

[0120] The main tasks of the GDHS are management of the calibrationprocess, management of updates of the gate configuration, and storage ofthe gate configuration and of the aircraft types.

[0121] During the set-up phase in isolated operation, it reads the gateconfiguration data from a file which has previously been produced by theGIP. In network operation, it reads the data via the GSS from theCNWS/CWPS, and stores this data internally.

[0122] The GSS illustrated in FIG. 14 comprises the gate manager (GM)and the watchdog (WD).

[0123] The main tasks of the GSS are to control the action sequencewithin the signal, to supply the GAMPS with calibration and aircraftdata, to produce time stamps and time inhibits, to trigger the watchdogand to interchange data with surrounding segments.

[0124] In isolated operation, the GSS provides the information input andoutput for the GOP via the GACS. In network operation, the interface tothe CNWS/CWPS is also controlled. The GSS transmits compressed livevideo images and status information to the CNWS/CWPS. Alternatively, thedocking sequences may be carried out via the CWPS. In this context, theinformation input and output for the GOP is interchanged via the GACSand via the CNWS with the CWPS.

[0125] During the set-up phase, system control is passed to the GDHS. Innetwork operation, the GSS supplies the GDHS with the transmission ofconfiguration data via the CNWS/CWPS.

[0126] During the calibration process, the GSS passes system control tothe GDHS. It transmits video images from the GAMPS to the GDHS. It usesthe GAMPS to verify calibration data. When the gate configuration isbeing updated, the docking mechanism is deactivated.

[0127] Upon completion of a docking sequence, the live video signals forthe last docking sequence can be repeated either by the PC monitor, thekeyboard or keypad and the mouse in isolated operation, or via thenetwork on the CWPS in network operation. It is impossible to initiate adocking sequence while a recorded video sequence is being viewed.

[0128] Maintenance tests may be initiated through the GOPS by the groundpersonnel or, controlled by the CNWS/CWPS, through the GSS.

[0129] The GSS triggers the watchdog periodically; otherwise, thewatchdog resets the PC.

[0130] The CNWS provides the communication between the CWPS and the GSSat the various gates, and vice versa. It transmits commands, data andcompressed video images; the latter are transmitted only whenspecifically requested.

[0131] The main tasks of the CWPS are: Display of the planned and actualgate occupancy, display of the status of a docking process for thecontrol center personnel, inputting gate configurations for a specificgate, inputting new aircraft models, data interchange with surroundingsystems, for example maintenance, flightplan data, or planned gateoccupancies.

[0132] The planned and the actual occupancy of gates may be displayedgraphically at any time. The global picture can be split up into anumber of smaller areas. One panel with all the gates occupied and theassociated calling symbols is shown. The control center personnel canoccupy a specific gate manually. Information about a specific gate andlive video transmission may be selected. The planned data is shown in aspecific block diagram. The planned occupancy may be changed or modifiedas required. The CWPS ensures that any change does not contravene gaterestrictions, for example by aircraft types being assigned to a gatewhich is unsuitable for such aircraft types.

[0133] The main functionalities of the AuxS are to assist thespecification of a gate, that is to say the coordinates of the centralline or center line and the stopping position, aircraft typespermissible for that gate, the specification of new aircraft models, anddisplaying the repetition of recorded docking sequences for evaluation.

[0134] These functionalities may be carried out at a separateworkstation. The data transmission from and to these functions iscarried out by means of a disk or some other medium, depending on therequired capacity.

[0135]FIG. 15 shows a schematic overview of how a docking guidancesystem according to the present invention is arranged in relation toother systems of an airport, e.g., a time reference system, an airfieldground lighting system, a user defined gate system, an airport database, and a central monitoring system.

[0136] The time reference system provides the docking guidance systemwith date and time information, as indicated by the arrow from the timereference system to the docking guidance system.

[0137] As indicated by the arrow from the airfield ground lightingsystem to the docking guidance system, the airfield ground lightingsystem sends signals regarding the status of lighting equipment for theairfield ground to the docking guidance system. The docking guidancesystem processes these status signals together with data from the otherairport systems shown in FIG. 15 and forwards, as a result, signals tothe airfield ground lighting system in order to control the lightingequipment for the airfield ground. For example, if an aircraft is dockedat a particular gate, the lighting equipment of the airfield ground iscontrolled in such a way that other aircraft, which have just landed andneed to be docked at a gate, for example, are not guided to theparticular gate that is currently occupied. In other words, the lightingequipment is controlled such that the particular gate, at which theaircraft is docked, is closed for other aircraft that are taxiing fromthe runway to a parking position in accordance with and/or in responseto route prescribed by the control tower of the airport.

[0138] The user defined gate system and the docking guidance systemexchange user defined input data and reporting messages regarding thestatus of the gate system, as indicated by the arrows between the userdefined gate system and the docking guidance system.

[0139] The airport database provides the docking guidance system withinformation regarding the current status of the gates, e.g., whether ornot a particular gate is currently occupied by an aircraft that hasdocked at the particular gate. In the reverse direction, the dockingguidance system provides the airport database with a time stamp so thatthe gate status information can be associated with date and timeinformation, for example.

[0140] The central monitoring system checks the overall operation of thedocking guidance system by sending check demands to the docking guidancesystem and by receiving check results from the docking guidance system.

[0141]FIG. 16 shows a software structure of the docking guidance system(DGS) according to the present invention as it is preferably configuredfor large airports having multiple terminals. The system architecture isdesigned as a star configuration whose center includes a server for acentral control device (CWP). Preferably, more than one CWP server isprovided so that the docking guidance system functions reliably even ifone of the CWP servers fails.

[0142] The CWP server is connected to a plurality of CWP clients via aDGS communications interface. These CWP clients are software packets,e.g., for operator stations for respective airport terminals or, in thecase of large terminals, for parts of the terminals themselves. Theoperator stations may be computers or simply operator displays togetherwith keyboards. The CWP clients are arranged in the computer network ofthe airport and control user interfaces of computers of a controller.The CWP clients execute inputs of the controller, messages from dockingguidance subsystems associated with each gate, etc. Moreover, the CWPoperator stations may receive data from a flight information system.

[0143] In addition, the CWP server is connected to the gates via a DGSnetwork interface. These gates are, for example, associated with standalone systems proposed by Siemens AG, such as Siemens Docking GuidanceSystems (SIDOGS). These stand alone systems are described in more detailbelow in connection with FIG. 20.

[0144] Furthermore, the CWP server is connected to interfaces toexternal systems, such as a surface movement guidance and control system(SMGCS), a central monitoring system (CMS), or other airport systems.

[0145]FIG. 17 shows a software structure of the docking guidance system(DGS) according to the present invention as it is preferably configuredfor mid-sized airports. In this preferred embodiment of the dockingguidance system according to the invention, the SIDOGS stand alonesystems are connected to one CWP operator station via the DGS networkinterface. The CWP operator station is arranged at a ground controlstation, for example, and is connected to interfaces to externalsystems, such as a surface movement guidance and control system (SMGCS),a central monitoring system (CMS), or other airport systems. The CWP maybe connected to the ground control station so that both dockinginformation and ground control information can be displayed on the samedisplay of a ground control station operator, for example. Thus, boththe taxiing process of aircraft on the airfield ground and the dockingprocess of aircraft at respective gates may be monitored and controlledby the ground control station. Furthermore, the CWP operator station mayreceive data from a flight information system.

[0146]FIG. 18 depicts a software structure of the docking guidancesystem (DGS) according to the present invention as it is preferablyconfigured for small airports. Here, the SIDOGS stand alone systems aredirectly connected to each other via the DGS network interface, which isa 100 Mbit Ethernet Hub, for example. In such an arrangement, theguidance of an aircraft to a parking position at a particular gate maybe carried out by a neighbor gate of the particular gate.

[0147] The software structures described above may be differentlydesigned in accordance with the desires and requirements of the airportoperator. In particular, the size of the airport, cost considerations,safety concerns, efficiency requirements, etc. determine the specificsoftware structure of a docking guidance system for a particularairport.

[0148]FIG. 19 shows a preferred architecture of the central controldevice of the docking guidance system according to the presentinvention. This preferred architecture includes software to control theterminals of an airport; interfaces to external systems, such as thoseshown in FIG. 15; a network card for communicating with the network ofthe docking guidance system; and an uninterruptable power system (UPS)to ensure uninterrupted power supply to the central control device. Theinterfaces to the external systems include, for example, an Ethernetinterface or a TCP/IP interface, an RS 422 interface, or an antenna. Thenetwork card of the central control device is provided to communicatewith a synchronous transmission mode type network having a data rate of155 Mbit/s, for example. Furthermore, the central control device isconnected to a control system for the apron of an airport. Thereby,relevant data regarding the status of the apron, for example, areincorporated into the docking guidance system. This results in improvedefficiency and improved safety of the docking process of aircraft, forexample. Furthermore, by connecting the CWP with the apron controlstation, both docking information and apron control information can bedisplayed on the same display of an apron control station operator, forexample. Thus, both the taxiing process of aircraft on the apron of theairport and the docking process of aircraft at respective gates may bemonitored and controlled by the apron control station.

[0149]FIG. 20 shows an overview of a preferred embodiment of the SiemensDocking Guidance System (SIDOGS). In this embodiment, each of gates 1 to13 is associated with a docking guidance subsystem. These dockingguidance subsystems are interconnected via a network having a data rateof 155 Mbit/s, for example. A particular docking guidance subsystemincludes a control computer, which is connected to and controls theoperation of a display, a TV camera, and a Local Operator Panel, asshown in an exemplary manner for gate 1. The entire arrangementincluding the network and the gates, together with their respectivedocking guidance subsystems, is connected to a central working position,or central control device, which monitors and controls the entire SIDOGSsystem.

[0150] The display includes information that indicates to the pilot ofan aircraft approaching the respective gate in which direction(s) theaircraft should be moved in order to reach its final parking position atthe gate. More specifically, the vertical arrow on the display indicatesthe distance the aircraft can or should be moved forward. The horizontalarrow on the display indicates where the aircraft should be movedlaterally. Since the final parking position depends on the type ofaircraft, the display also indicates the aircraft type recognized by thedocking guidance subsystem, e.g., A320. In this way, the pilot is ableto check whether the correct aircraft type has been recognized.

[0151] In a preferred embodiment of the display, the vertical arrowreduces its size as the pilot moves the aircraft forward. The lateralmovement of the aircraft may be indicated to the pilot by two horizontalarrows, which face each other. If the pilot moves the aircraftlaterally, these two arrows move accordingly on the display. In theexemplary situation shown on the display of gate 1 in FIG. 20, the pilotneeds to move the aircraft forward and further to the right in order toreach the final parking position. As long as the point, at which the twotips of the horizontal arrows touch each other, lies off-centered withregard to the tip of the vertical arrow, the pilot must adjust thelateral position of the aircraft accordingly. Once this point liesprecisely above the tip of the vertical arrow, the aircraft has reachedthe correct lateral coordinate of the final parking position. The pilotcan now move the aircraft straight ahead so that the vertical arrowbecomes shorter and shorter until it finally disappears. At that point,the aircraft has reached its final parking position.

[0152] The display may be located in the vicinity of the gate so thatthe pilot watches the display through the windshield of the aircraft'scockpit. Alternatively, the display information may be transmitted intothe cockpit via a wireless link. In this case, the pilot monitors themovement of the aircraft on a display located in the cockpit.

[0153] The TV camera delivers information regarding the type andmovement of the aircraft to the control computer, as described earlierin connection with FIGS. 1 and 2, in order to update the information onthe display.

[0154] Should the network fail, the docking guidance subsystem for eachgate is manually operated by the respective local operator panel.

[0155]FIG. 21 shows an exemplary screen display of the central workingposition, or central control device, of FIG. 20. This screen display, aswell as other screen displays used in the docking guidance systemaccording to the present invention, may be a black-and-white display ora color display A screen section in the upper right corner shows a livevideo display of the aircraft approaching the gate. The video display isprovided by the TV camera of FIG. 20, for example. Thereby, an operatoris able to monitor the actual docking process of the aircraft.

[0156] A screen section in the upper left corner displays scheduleinformation for individual gates, i.e., which aircraft type is scheduledto be docked at which gate for which time of the day. For example, asshown in FIG. 21, an aircraft of the B737-2 type is scheduled to bedocked at gate B30 approximately between 8:30 and 10:15.

[0157] A lower section of the screen display of FIG. 21 shows aschematic overview of the gate arrangement of a particular airport andwhat the current status of the gates . For example, gate B36 is closed,as shown in FIG. 21. In addition, this screen section indicates whichaircraft type is docked at which gate and what the current status of therespective gate is, e.g., “prepared”, “stop”, or “closed”. In a“prepared” status, the gate is ready for docking an aircraft, forexample. In a “stop” status, the gate is currently occupied by anaircraft docked at the gate, for example. In a “closed” status, the gateis simply closed for operation.

[0158]FIG. 22 represents a preferred calibration system for calibratingthe angular field and/or position of the TV camera or video camera ofthe docking guidance system according to the present invention. If thecamera is not calibrated, the camera will, e.g. over time, delivererroneous information as to the current position of an aircraftapproaching the respective gate. This, in turn, results in erroneousinformation on the respective display shown in FIG. 20, so that thepilot is unable to properly guide the aircraft to its parking position.

[0159] The SIDOGS system has the following functionalities. First,access to the system is protected by passwords. Furthermore, severaloperator terminals may be arranged in the network of the system anddifferent authorizations can be granted to the users of the system. Inaddition, interactions of the system operators with the system can belogged and error messages may be printed on the operator screens or onan alarm printer. Messages regarding the status of a selected gate areexchanged in the system and a live video picture delivered by the TVcamera or the video camera is displayed in the control room of thesystem.

[0160] Since SIDOGS includes a schedule system as described above, thedocking process for aircraft can be started automatically at a scheduledtime. The network connections to the gate computers are automaticallytested and a graphical user interface is provided for installing newgates, i.e., for integrating monitoring and control functions fordocking guidance subsystems associated with additional gates into thesoftware of the docking guidance system. For troubleshooting purposes,test programs may be executed and, if there is an emergency situation,the system operator may trigger an emergency stop of the system.Finally, the docking process may be manually started by the operator, ifnecessary or desired.

[0161] Since the SIDOGS operating system is based on the well-knownWindows (NT) software, the SIDOGS system has the advantage that nospecial training for maintenance personnel is necessary. In addition,since the interfaces to the external systems are open interfaces, theexternal systems are easily connected to the SIDOGS system. SIDOGS canbe remotely accessed via a modem in order to carry out maintenanceduties, for example. Finally, it is a further advantage of the SIDOGSsystem that additional gates can be easily integrated into the system.

[0162] The process of docking an aircraft at a gate is carried out inthe following exemplary manner. First, the operator of the SIDOGS systemselects the gate at which an approaching aircraft is to be docked.Second, the type of the approaching aircraft is manually orautomatically selected at either the Gate Operator Panel (GOP) of therespective gate or at the control center of the system. Subsequently,video data of the aircraft approaching the gate, which are detected bythe TV camera or the video camera of the respective gate, aretransmitted to the control center. If necessary, the operator in thecontrol center can influence the docking process at any time. Forexample, in case of an emergency situation, the system operator iscapable of issuing an “emergency stop” signal, which will halt thedocking process in progress. Finally, status messages of the dockingprocess are transmitted to the control center, in accordance with whichthe docking process is monitored and controlled.

[0163] The processing of the video data, e.g., gray tone images of theaircraft approaching the gate, at which it is to be docked, is describedin more detail in connection with FIGS. 1 to 4 above. These gray toneimages are supplied to an evaluation unit. In a first step, theevaluation unit filters the gray tone images to recognize edges in theimage. Subsequently, filtering in the time domain is used to extractedges which move over time so that moving objects can be distinguishedfrom stationary objects. Certain outlines of the aircraft are thencompared with templates previously stored in the evaluation unit.Thereby, the aircraft type and the current position of the aircraft arerecognized by the evaluation unit. The resulting data are forwarded tothe display, which is arranged outside the aircraft and/or inside theaircraft, based on which the pilot moves the aircraft such that itfinally reaches its final parking position.

[0164] The above description of the preferred embodiments has been givenby way of example. From the disclosure given, those skilled in the artwill not only understand the present invention and its attendantadvantages, but will also find apparent various changes andmodifications to the structures and methods disclosed. It is sought,therefore, to cover all such changes and modifications as fall withinthe spirit and scope of the invention, as defined by the appendedclaims, and equivalents thereof.

What is claimed is:
 1. A docking guidance system for guiding an aircraftto a parking position of an airport, comprising: a server of a centralcontrol device; a plurality of operator stations of the control device,which are connected to the server of the central control device via acommunications interface, wherein each of the operator stations isconfigured for a respective terminal of the airport to monitor a guidingprocess of the aircraft; a plurality of stand alone systems connected tothe server of the central control device via a network interface,wherein each of the stand alone systems is associated with a respectivegate of the airport, at which the aircraft is to be guided to theparking position; and at least one interface to connect the server ofthe central control device to external airport systems.
 2. The dockingguidance system of claim 1, wherein a respective one of the plurality ofstand alone systems that is associated with the respective gate of theairport, at which the aircraft is to be guided to the parking position,is configured to receive guidance data regarding the guidance of theaircraft to the parking position; wherein the respective one of theplurality of stand alone systems is configured to forward the guidancedata to the server of the central control device via the networkinterface; and wherein the server of the central control device isconfigured: to process the guidance data, to send first control signalsresponsive to the guidance data to the external airport systems via theinterface, to send second control signals responsive to the guidancedata to at least one of the plurality of operator stations via thecommunications interface, to process external-airport-systems-dataresponsive to the first control signals and received from the externalairport systems via the interface, to process operator-station-dataresponsive to the second control signals and received from the at leastone operator station via the communications interface, to forward thirdcontrol signals responsive to the external-airport-systems-data to therespective one of the plurality of stand alone systems via the networkinterface, and to forward fourth control signals responsive to theoperator-station-data to the respective one of the plurality of standalone systems via the network interface.
 3. A docking guidance systemfor guiding an aircraft to a parking position of an airport, comprising:an operator station of a central control device; a plurality of standalone systems connected to the operator station via a network interface,wherein each stand alone system is associated with a respective gate ofthe airport, at which the aircraft is to be guided to the parkingposition; and at least one interface to connect the operator station toexternal airport systems.
 4. The docking guidance system of claim 3,wherein a respective one of the plurality of stand alone systemsassociated with the respective gate of the airport, at which theaircraft is to be guided to the parking position, is configured toreceive guidance data regarding the guidance of the aircraft to theparking position; wherein the respective one of the plurality of standalone systems is configured to forward the guidance data to the operatorstation of the central control device via the network interface; andwherein the operator station of the central control device isconfigured: to process the guidance data, to send first control signalsresponsive to the guidance data to the external airport systems via theinterface, to process external-airport-systems-data responsive to thefirst control signals and received from the external airport systems viathe interface, and to forward second control signals responsive to theexternal-airport-systems-data to the respective one of the plurality ofstand alone systems via the network interface.
 5. A docking guidancesystem for guiding an aircraft to a parking position of an airport,comprising a plurality of stand alone systems interconnected via anetwork, wherein each stand alone system is associated with a respectivegate of the airport, at which the aircraft is to be guided to theparking position.
 6. The docking guidance system of claim 5, wherein afirst stand alone system associated with the respective gate of theairport, at which the aircraft is to be guided to the parking position,is configured to receive data regarding the guidance of the aircraft tothe parking position, and wherein the first stand alone system isconfigured to forward the data, via the network, to a second stand alonesystem, at which an operator monitors and influences the guidance of theaircraft at the respective gate associated with the first stand alonesystem.